1. Field of the Invention
Embodiments of the present invention generally relate to a perpendicular magnetic recording (PMR) write head.
2. Description of the Related Art
The heart of a computer is a magnetic disk drive which typically includes a rotating magnetic disk, a slider that has read and write heads, a suspension arm above the rotating disk and an actuator arm that swings the suspension arm to place the read and/or write heads over selected circular tracks on the rotating disk. The suspension arm biases the slider towards the surface of the disk when the disk is not rotating but, when the disk rotates, air is swirled by the rotating disk adjacent an air bearing surface (ABS) of the slider causing the slider to ride on an air bearing a slight distance from the surface of the rotating disk. When the slider rides on the air bearing, the write and read heads are employed for writing magnetic impressions to and reading magnetic signal fields from the rotating disk. The read and write heads are connected to processing circuitry that operates according to a computer program to implement the writing and reading functions.
In order for the magnetic disk drive to function properly, the disk drive must be able to function even in the presence of high external stray magnetic fields. The stray magnetic fields can impact both write and read operations. One solution is to widen the return pole at the ABS, or to widen the wrap around shield at the ABS to decrease the flux density due to stray magnetic field at ABS. Additionally, larger return poles and increasing the size of the wrap around only mitigate the effect of stray magnetic fields but do not eliminate them in the presence at high stray magnetic field. Additionally, if the yoke and/or return pole are too small, then the stray magnetic fields could alter the saturation rate of the return pole/yoke and thus, shift the optimum point of operation for the write head.
Therefore, there is a need in the art for preventing stray magnetic fields from interfering with write heads without reducing performance capabilities of the write head. Additionally, this protection should be implemented with a process that is compatible to with the existing fabrication process.